Gas turbine engines used for powering aircraft, for example, include a compressor for compressing ambient air for providing compressed air to a combustor disposed axially downstream therefrom. Fuel is mixed with the compressed air in the combustor and ignited for generating combustion gases which are discharged therefrom axially downstream to a high pressure turbine which powers the compressor.
The fuel is mixed with the compressed air in the combustor typically in a plurality of circumferentially spaced apart carburetors each including a fuel injector and an air swirler. The carburetors are typically disposed in the dome of the combustor radially between the outer and inner combustion liners thereof. Since a plurality of circumferentially spaced carburetors are utilized, the resulting fuel/air mixtures discharged therefrom inherently provide a circumferentially varying profile with a corresponding circumferentially varying temperature distribution in the combustion gases generated therefrom.
A pattern factor is a conventionally known parameter which indicates the amount of circumferential variation of the combustion gas temperature around the combustor outlet and has a value ranging between about 0.25-0.30 for high performance combustors. Improvements in the pattern factor are being considered with levels reduced to about 0.15 which is a substantially low value requiring improved circumferential uniformity of the fuel/air mixture being discharged from the carburetors of the combustor.
The shorter a combustor is made in the axial direction for reducing weight and cooling-air requirements thereof, the greater is the difficulty in achieving reduced pattern factor.